Dexamethasone treatment of brain tumor patients: effects on regional cerebral blood flow, blood volume, and oxygen utilization.

Regional values for cerebral blood flow, blood volume, oxygen extraction fraction, and oxygen utilization were measured, using PET, in 10 brain tumor patients before and after treatment with dexamethasone. Dexamethasone treatment decreased cerebral blood flow and blood volume and increased the fractional extraction of oxygen throughout the brain without affecting oxygen utilization. Dexamethasone probably causes direct vasoconstriction of cerebral blood vessels.